Hadoop ConnectException: Connection refused的一种解决办法

跟着视频学习天气案例，把代码敲好，准备提交运行时才发现集群没启动。然后在node02、node03、node04使用zkServer.sh start启动ZooKeeper，然后在node01使用start-dfs.sh启动hdfs，最后使用start-yarn.sh启动yarn，最后使用hadoop jar MyTQ.jar com.sxt.hadoop.mr.tq.MyTQ启动程序，结果报如下错误。

[root@node01 ~]# hdfs jar MyTQ.jar com.sxt.hadoop.mr.tq.MyTQ
Error: Could not find or load main class jar
[root@node01 ~]# hadoop jar MyTQ.jar com.sxt.hadoop.mr.tq.MyTQ
// :: INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm2
// :: INFO retry.RetryInvocationHandler: Exception while invoking getNewApplication of class ApplicationClientProtocolPBClientImpl over rm2 after  fail over attempts. Trying to fail over after sleeping for 28627ms.
java.net.ConnectException: Call From node01/192.168.30.136 to node04: failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:)
    at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:)
    at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:)
    at org.apache.hadoop.ipc.Client.call(Client.java:)
    at org.apache.hadoop.ipc.Client.call(Client.java:)
    at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:)
    at com.sun.proxy.$Proxy13.getNewApplication(Unknown Source)
    at org.apache.hadoop.yarn.api.impl.pb.client.ApplicationClientProtocolPBClientImpl.getNewApplication(ApplicationClientProtocolPBClientImpl.java:)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:)
    at java.lang.reflect.Method.invoke(Method.java:)
    at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:)
    at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:)
    at com.sun.proxy.$Proxy14.getNewApplication(Unknown Source)
    at org.apache.hadoop.yarn.client.api.impl.YarnClientImpl.getNewApplication(YarnClientImpl.java:)
    at org.apache.hadoop.yarn.client.api.impl.YarnClientImpl.createApplication(YarnClientImpl.java:)
    at org.apache.hadoop.mapred.ResourceMgrDelegate.getNewJobID(ResourceMgrDelegate.java:)
    at org.apache.hadoop.mapred.YARNRunner.getNewJobID(YARNRunner.java:)
    at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:)
    at org.apache.hadoop.mapreduce.Job$.run(Job.java:)
    at org.apache.hadoop.mapreduce.Job$.run(Job.java:)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:)
    at org.apache.hadoop.mapreduce.Job.submit(Job.java:)
    at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:)
    at com.sxt.hadoop.mr.tq.MyTQ.main(MyTQ.java:)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:)
    at java.lang.reflect.Method.invoke(Method.java:)
    at org.apache.hadoop.util.RunJar.run(RunJar.java:)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:)
Caused by: java.net.ConnectException: Connection refused
    at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:)
    at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:)
    at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:)
    at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:)
    at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:)
    at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:)
    at org.apache.hadoop.ipc.Client$Connection.access$(Client.java:)
    at org.apache.hadoop.ipc.Client.getConnection(Client.java:)
    at org.apache.hadoop.ipc.Client.call(Client.java:)
    ...  more

解决办法：在node03和node04上使用yarn-daemon.sh start resourcemanager启动resourcemanager。

搞了两晚上才找到原因，对集群角色不熟，导致出了问题也不知道怎么回事，基础还是得打扎实啊